Studies are underway of the digestibility and utilization of the protein and energy of oats when providing 22 to 66% of calories in diet of infants. During prolonged feeding at the highest levels, the absorption of trace minerals will be studied: Zn, Fe, Cu, Mg, Ca and PO4, possibly Mn, Cr, and others. The ability of wheat-legume and rice-legume mixtures to satisfy the protein needs of infants, and their effects on mineral absorption are being studied. Protein requirements of convalescent malnourished infants (6-11.9 months) and small children (12-33 months) are being determined with a 60-40 whey-casein formula at 8.0, 6.7 and 5.5% protein calories for the younger group, and at 6.4 and 4.7% for the older group. Adequacy is judged by anthropometry, standard biochemical indices, and body composition by H218O and bromide dilutions for total body water and extracellular water estimations, respectively.